mineral
Turquoise
Turquoise (Hydrated phosphate of copper and aluminium), CuAl6(PO4)4(OH)8·4H2O
Hardness: 5-6 (Mohs scale); Color: Sky blue to blue-green; Luster: Waxy to subvitreous; Crystal Structure: Triclinic (usually cryptocrystalline); Specific Gravity: 2.6-2.9.
- Hardness
- 5-6 (Mohs scale)
- Color
- Sky blue to blue-green
- Luster
- Waxy to subvitreous
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Physical properties
Hardness: 5-6 (Mohs scale); Color: Sky blue to blue-green; Luster: Waxy to subvitreous; Crystal Structure: Triclinic (usually cryptocrystalline); Specific Gravity: 2.6-2.9.
Formation & geological history
Secondary mineral formed by the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals. It is often found in arid climates within volcanic rocks or sedimentary phosphorus-rich environments.
Uses & applications
Primarily used as a gemstone in jewelry, decorative carvings, and inlay work. Highly valued for its unique color in various cultures.
Geological facts
Turquoise is one of the oldest gemstones in human history, dating back to 3000 BCE in Ancient Egypt. Many specimens today are 'stabilized' with resin to improve durability and color.
Field identification & locations
Identify by its robin-egg blue color and dark matrix veins (often limonite or sandstone). Found commonly in the Southwestern USA, Iran, and China. In the field, look for opaque blue-green nodules in weathered host rock.
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Potassium Feldspar (Orthoclase)
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Mineral/Rock